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Fossil leaf species from the Fox Hills Formation (Upper Cretaceous: North Dakota, USA) and their paleogeographic significance

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Abstract

Seven fossil leaf species are described from impression fossils collected from the Upper Cretaceous (Maastrichtian) Fox Hills Formation in south-central North Dakota, USA. They are Marmarthia johnsonii n. sp., Nilssoniocladus yukonensis n. comb., Nilssoniocladus comtula n. comb., Mesocyparis borealis, Rhamnus salicifolius, Paloreodoxites plicatus, and Zingiberopsis magnifolia. These species represent some of the elements of the Fox Hills flora that have paleogeographic ranges to the northwest (N. yukonensis, N. comtula, and M. borealis) and to the southwest (M. johnsonii, R. salicifolius, P. plicatus, and Z. magnifolia) of the Fox Hills type area. The identification and reappraisal of these species represent an effort to understand the biogeographic relationships of Late Cretaceous floras across the Northern Hemisphere.

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... The Seafood Salad locality represents one of the oldest and most well-preserved Maastrichtian megafloras reported to date from northeastern Montana, and can be directly tied to the local vertebrate faunal record (e.g., Wilson, 2005Wilson, , 2014 and existing studies of palynoflora (e.g., Hotton, 2002). We describe the taxonomic composition and diversity of the flora and compare it with previously reported Late Cretaceous megafloral records from the Western Interior (e.g., Dorf, 1942;Shoemaker, 1966;Hickey, 1977;Johnson et al., 1989;Johnson, 1989Johnson, , 1992Johnson, , 1996Johnson, , 2002Johnson and Hickey, 1990;Wilf and Johnson, 2004;Peppe et al., 2007;Arens and Allen, 2014). Our goal is to better understand the temporal and spatial variation in vegetation and paleofloral diversity in the northern Great Plains during the latest Cretaceous. ...
... We assessed the affinity of each morphotype to taxa that have been described in the published literature of KPB-age floras from the northern Great Plains region (Table A1). Fourteen of our 34 morphotypes are attributed to published species or to published or unpublished morphotypes from the Late Cretaceous (Dorf, 1942;Johnson, 1989Johnson, , 1996Johnson, , 2002Peppe et al., 2007;Arens and Allen, 2014;K. Johnson, personal communication, June 23, 2018). ...
... Morphotypes are each assigned with an alphanumeric code; these codes were assigned in order of major leaf architecture (see Table A3). These specimens use MT as the prefix to distinguish this study from work in North Dakota (which used FH, HC, and FU prefixes;Johnson, 1989;Peppe et al., 2007) and at other locations in Montana (which used FP prefix;Arens and Allen, 2014). ...
Article
The Cretaceous-Paleogene (K/Pg) boundary marks a mass extinction resulting in global biotic turnover. Exposures of the Hell Creek Formation in northeastern Montana contain some of the most well-studied vertebrate localities recording this mass extinction; however, very little is known of the floral record in this area. As part of an effort to reconstruct floral changes across the K/Pg in northeastern Montana, this study presents a taxonomically diverse flora from the Seafood Salad locality, located ∼ 65 m below the K/Pg boundary in the Hell Creek Formation, Garfield County, Montana. Leaves, stems, and reproductive structures (e.g., cones and seeds) are preserved as compression and impression fossils in massive, bedded siltstones and very fine sandstones. Seafood Salad is significant in that it is represents a “pre-disaster” community approximately 1.3 m.y. before the K/Pg mass extinction. We interpret the plants in these deposits as reflecting a local riparian community. The vegetation was taxonomically diverse and dominated by angiosperm trees; it also included abundant conifer specimens of a few taxa and relatively few ginkgoes and ferns. We describe 34 morphotypes and propose taxonomic affinities to modern groups and to fossil taxa from contemporaneous-age deposits in Montana and North Dakota. The Seafood Salad flora shares several taxa with other Late Cretaceous floras of the Western Interior, but substantial differences in taxonomic composition and relative abundances among these assemblages indicate that regional plant communities in the latest Cretaceous were spatially heterogeneous, rapidly changing, or both.
... Позднее листья N. serotina были найдены в различных регионах Северной Пацифики: на Северо-Востоке России (Щепетов и др.Северной Дакоте (Peppe et al., 2007). ...
... Пеппе с соавторами (Peppe et al., 2007) (Герман, 2011). Они были обнаружены в слоях Нижний Киллик (бассейн р. ...
... Наиболее широкое распространение N. serotinа имела в маастрихте. В это время она известна из отложений каканаутской свиты и нижней подсвиты рарыткинской свиты, Корякское нагорье (Головнева, 1994), а также из формаций Edmonton и Brazeau в Западной Канаде (Bell, 1949) и формаций Fox Hills и Hell Creek в Северной Дакоте, США (Peppe et al., 2007). ...
Article
Variability of Nilssonia serotinaleaves was studied by the material from the Sakhalin, from the Maastrichtian deposits of the Kakanaut Formation (Koryak Upland), the upper Albian-lower Turonian deposits of the Krivorechenskaya Formation (Anadyr River Basin) and the Santonian-upper Campanian deposits of the Chignik Formation (Alaska). Type material of Nilssonia serotina Heer from thе Santonian deposits of upper part of the Arkovo Formation of Sakhalin restudied for the first time. This collection is stored in Komarov Botanical Institute. A lectotype was selected, and an extended specimen diagnosis was defined. Leaves of N. serotina are varied from nearly entier with rare dissections, to those having numerous triangular or trapezoidal segments. Distribution of Nilssonia serotina from the Albian to the Paleoсеne was revealed. This species was distributed on the Sakhalin, Northeastern Russia, Western Canada, Alaska and North Dakota (USA).
... Позднее листья N. serotina были найдены в различных регионах Северной Пацифики: на Северо-Востоке России (Щепетов и др.Северной Дакоте (Peppe et al., 2007). ...
... Пеппе с соавторами (Peppe et al., 2007) (Герман, 2011). Они были обнаружены в слоях Нижний Киллик (бассейн р. ...
... Наиболее широкое распространение N. serotinа имела в маастрихте. В это время она известна из отложений каканаутской свиты и нижней подсвиты рарыткинской свиты, Корякское нагорье (Головнева, 1994), а также из формаций Edmonton и Brazeau в Западной Канаде (Bell, 1949) и формаций Fox Hills и Hell Creek в Северной Дакоте, США (Peppe et al., 2007). ...
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Nilssonia serotina Heer изучена на материале из сантон-нижнекампанских отло-жений верхней части арковской свиты Сахалина, маастрихтских отложений каканаутской свиты Корякского нагорья, верхнеальбских-нижнетуронских отложений кривореченской свиты бассей-на р. Анадырь и сантон-нижнекампанских отложений формации Чигник на Аляске. Переизучен типовой материал этого вида, описанный О. Геером с Сахалина. Выбран лектотип N. serotina и дан расширенный диагноз. Листья данного вида могут варьировать от почти цельных с небольшим ко-личеством рассечений до сегментированных с многочисленными треугольными, трапециевидны-ми или прямоугольными сегментами. Проведено сравнение N. serotina с другими познемеловыми Nilssonia из Северной Пацифики. Вид N. serotina существовал с альба до палеоцена и был распро-странен на территории Сахалина, Северо-Востока России, Западной Канады, Аляски и Северной Дакоты (США). Ключевые слова: цикадовые, Nilssonia serotina, поздний мел, Северная Пацифика. ВВЕДЕНИЕ Род Nilssonia Brongniart — один из наиболее известных представителей мезозойских цикадовых. Он был описан А. Броньяром (1825) по листьям из нижнеюрских отложений Швеции. Данный род известен с позднего триаса, а его расцвет приходится на юру (Taylor et al., 2009). В раннем мелу коли-чество видов Nilssonia сокращается, а позднемеловые представители единичны. Одним из последних представителей рода является Nilssonia serotina Heer. Остатки, на основа-нии которых был описан данный вид, были в 1860 году собраны Ф. Б. Шмидтом в районе Мгачи на Сахалине из отложений, впоследствии отнесенных к верхней части арковской свиты. Коллекция Шмидта была переслана O. Гееру, который опубликовал первое описание ископаемой флоры о. Са-халин и описал ряд новых видов, в том числе и N. serotina (Heer, 1878a). Позднее листья N. serotina были найдены в различных регионах Северной Пацифики: на Севе-ро-Востоке России (Щепетов и др.
... When reviewing these records, which are arranged more or less chronologically, please note that Berry (1922, p. 171) erroneously reported that "C." panduratus initially had been described from the Mesaverde Formation (no locality given), but that he later corrected this report by acknowl- edging that, at the time, "C." panduratus was known only from the Vermejo and Ripley Formations and not the Mesaverde Formation (Berry, 1925, p. 24). Key to lettered paleogeographic features: (a) northern shoreline of the WIS according to Erickson (1978Erickson ( , 1999, Lillegraven and Ostresh (1990), Robinson Roberts and Kirschbaum (1995), and Kennedy et al. (1998); (b) southern shoreline of the WIS according to Lehman (1987) and Blakey (2014); (c) dispersal route for land plants between Asia and western North America in the late Maastrichtian ( Peppe et al., 2007;Zakharov et al., 2011); (d) eastern margin of the WIS and general location (e) of a large island or archipelago according to Williams and Stelck (1975). Local paleogeographic map (modified from Miller and McKinney, 2016): Position of western shoreline of the WIS during the Baculites clinolobatus ammonite biozone as reconstructed by Cobban et al. (1994), Landman and Cobban (2003), Slattery et al. (2015), and Miller and McKinney (2016). ...
... Because the Raton Basin is placed along the southern shoreline of the WIS in some of the paleogeo- graphic models discussed above (see Lehman, 1987;Blakey, 2014), the transitional-marine biostratigraphy of the basin can be used to test the key predictions of these models. In particular, evidence for the biogeographic exchange of ter- restrial taxa between eastern and western North America can be evaluated to determine whether the timing of bio- geographic range expansion coincides with models that close the WIS to the Gulf of Mexico in the late Campanian (see Lehman, 1987;Blakey, 2014) or models that close the WIS to the Arctic Ocean in either the early Maastrichtian (see Lillegraven and Ostresh, 1990;Robinson Roberts and Kirschbaum, 1995) or the late Maastrichtian (see Erickson, 1978Erickson, , 1999Peppe et al., 2007). ...
... integerrima, could have dispersed from the Russian Far East into western North America during the late Maastrichtian. By the late Maastrichtian, a Beringian land bridge between the Russian Far East and western North America had been established ( Peppe et al., 2007;Zakharov et al., 2011). This dispersal route explains, for example, the appearance of Araliaephyllum polevoi (Kryshtofovich, 1918), which was previously characteristic of the Russian Far East, in western North America during the late Maastrichtian (Johnson, 2002;Nichols and Johnson, 2008). ...
Article
There is considerable debate regarding the paleogeography of the Western Interior Seaway (WIS) near the close of the Cretaceous. To investigate this issue, the paleogeographic implications of recent advancements in the biostratigraphy of the lower to upper Maastrichtian, transitional-marine strata in the Raton Basin are explored. In southern Colorado, the western shoreline of the WIS should be shifted about 100 km farther west than current projections for the end of the early Maastrichtian. Strong marine connections among the WIS, the Gulf of Mexico, and the North Atlantic appear to have persisted at least until the end of the early Maastrichtian. A marine connection between the WIS and the Gulf of Mexico is projected to have lasted through the end of the Cretaceous. Closure of the WIS to the Arctic Ocean is projected to have occurred earlier and farther north than other models, which close the WIS to the Arctic Ocean through the formation of the Dakota Isthmus in the latest Maastrichtian. Closure of the WIS in Canada during the early late-Maastrichtian (Hoploscaphites birkelundae ammonite biozone) appears to have permitted the dispersal of land plants, such as "Cissites" panduratus and Credneria protophylloides, among landmasses previously isolated by epeiric seaways covering much of North America and western Greenland during the Late Cretaceous and is consistent with preexisting biostratigraphic constraints on the paleogeography of the WIS.
... Stratigraphic evidence for the isthmus has been removed by erosion across the eastern margin of the Williston Basin and Sioux Arch. Paleontological evidence supporting such a deposystem, a sealevel sand plain, has been accumulated by Erickson and colleagues since the initial hypothesis of the Dakota Isthmus was presented (Erickson, 1978(Erickson, , 1999Bouchard, et al., 2002;Carpenter, et al., 2002Carpenter, et al., , 2003Hoganson et al., 2007;Peppe, et al., 2007;Erickson, et al., 2008). ...
... An outcrop of the Linton Member of the Fox Hills Formation in Emmons County, ND, has produced an interesting assortment of paleontological evidence indicating an estuarine complex ( Figure 5). Peppe, et al., (2007) recognized more than 60 species of macroflora at the site. We estimate that there maybe as many as 250 distinct palynomorph types present in the samples used for this study. ...
... nov., with those of the extant Osmunda species (Table 1) Fossil records of Osmunda are common in the Mesozoic and Cenozoic strata of the Northern Hemisphere. Numerous compression specimens from the Cretaceous (Vega et al., 2006;Peppe et al., 2007;Jud et al., 2008;Nel et al., 2008) have been described in which Osmunda has tongue-shaped and asymmetrical pinnae, which differ from those of the current fossil specimens that have linear-lanceolateshaped and symmetrical pinnae. Furthermore, the pinnae from the Mesozoic are usually smaller than the pinnae described in the current fossil specimens. ...
... The Fox Hills flora is from the Linton Member of the Fox Hills Formation and is late Maastrichtian in age (c. 66 Ma; Peppe, 2003;Peppe et al., 2007; Table 1). We grouped these taxa by floral zone following Peppe (2009Peppe ( , 2010. ...
Article
• Paleobotanists have long used models based on leaf size and shape to reconstruct paleoclimate. However, most models incorporate a single variable or use traits that are not physiologically or functionally linked to climate, limiting their predictive power. Further, they often underestimate paleotemperature relative to other proxies. • Here we quantify leaf-climate correlations from 92 globally distributed, climatically diverse sites, and explore potential confounding factors. Multiple linear regression models for mean annual temperature (MAT) and mean annual precipitation (MAP) are developed and applied to nine well-studied fossil floras. • We find that leaves in cold climates typically have larger, more numerous teeth, and are more highly dissected. Leaf habit (deciduous vs evergreen), local water availability, and phylogenetic history all affect these relationships. Leaves in wet climates are larger and have fewer, smaller teeth. Our multivariate MAT and MAP models offer moderate improvements in precision over univariate approaches (± 4.0 vs 4.8°C for MAT) and strong improvements in accuracy. For example, our provisional MAT estimates for most North American fossil floras are considerably warmer and in better agreement with independent paleoclimate evidence. • Our study demonstrates that the inclusion of additional leaf traits that are functionally linked to climate improves paleoclimate reconstructions. This work also illustrates the need for better understanding of the impact of phylogeny and leaf habit on leaf-climate relationships.
... This is emphasized by records of two species from the Santonian-Campanian Pautû t flora of West Greenland (Boyd 1992). These specimens, or the poorly preserved examples of Zamites in the Coniacian-Campanian of western Canada (Bell 1957), appear to be the youngest records of Bennettitales in the Northern Hemisphere, given that Maastrichtian examples of Nilssonia from northwestern Russia (Vakhrameev 1991) and western Canada (Bell 1949) likely represent cycadaleans (Peppe et al. 2007;Pott et al. 2007). Unfortunately, pollen records are of little assistance in tracking the stratigraphic range and geographic distribution of the Bennettitales. ...
Article
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Several small pinnate leaves of early Oligocene age from Cethana, Tasmania, are newly described and found to be conspecific with Anomozamites muelleri Ettingsh. recorded from coeval strata at Emmaville, northern New South Wales. These fossils are most probably referable to the Bennettitales on the basis of leaf size, leaflet shape, and venation patterns, in the absence of diagnostic cuticular details. They are transferred to Ptilophyllum on the basis of leaflet morphology and represent the youngest putative bennettitalean remains yet documented. Their occurrence reinforces previous arguments that the highest-paleolatitude fragments of southeastern Gondwana provided moist temperate refugia for the survival of Mesozoic gymnosperm taxa well into the Cenozoic.
... The K/Pg boundary, and the latest Cretaceous and earliest Paleocene floras have been studied extensively in the Williston Basin (e.g., Berry, 1934;Brown, 1939Brown, ,1962Shoemaker, 1966;Williams, 1988;Johnson, 1989;Johnson et al., 1989;Johnson and Hickey, 1990;Johnson, 1992Johnson, ,1996Johnson, , 2002Peppe, 2003;Wilf et al., 2003;Wilf and Johnson, 2004;Smrecak, 2006;Wilf et al., 2006;Peppe et al., 2007). These studies have shown a marked difference between Cretaceous and Paleocene floras. ...
... Fossil floras can provide important insights into land-plant evolution, paleocology, biogeography and climate (e.g., Hickey and Doyle 1977;Graham 1999;Hoffman and Stockey 1999;Manchester 1999;Peppe et al. 2007). A traditional floristic monograph includes taxonomic and systematic descriptions of all entities in a flora. ...
Article
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We describe 28 fossil plant morphotypes from the Aspen Shale flora (Cretaceous: middle to late Albian) in southwestern Wyoming. This impression flora includes 6 ferns, 1 sphenopsid, 2 conifers, 17 dicotyledonous angiosperm (dicot) leaves and 2 dicot reproductive structures. The Aspen Shale megaflora is most similar to that of Subzone IIB of the Potomac Group of the eastern United States. Analysis of the Aspen Shale sedimentology and botanical composition shows occupation of open, paludal sites by a succession of progressively more complex plant communities. Like other middle Cretaceous floras, these data suggest that early angiosperms were weedy, herbaceous to shrubby, early successional competitors to ferns on open substrates. The description and illustration of the Aspen Shale morphotypes is presented as an example of how an entire flora can be described and analyzed before full taxonomic determinations have been made.
... The sites in the present study are of late Paleocene age.Plant fossil localities --A rich fossil record of plants is known for the Williston Basin from late Cretaceous to early Eocene strata. Among the plants the transition from the late Cretaceous floras of Hell Creek Formation(Johnson, 2002;Peppe et al., 2007) into the early Paleocene Fort Union Formation has been documented in southwestern North Dakota. Early to middle Paleocene floral change has been described for the Ludlow and Tongue River Members of the Fort Union group(Peppe, in press). ...
... This point of view seems to be problematic (as it was al− ready for Berry 1916) for the following reasons: (i) serrate and (apparently) integrimarginate leaves (otherwise identi− cal) are present in the same levels; (ii) variation between ser− rate and integrimarginate leaves has been documented in a contemporary species of similar leaf architecture, namely Helleborus lividus Aiton, 1789 (the type is serrate, while H. lividus var. integrifolius de Candolle, 1805 has no teeth; Saporta and Marion 1873); (iii) the serrate margin may roll down into the rock, wherefore the leaves appear as entire: such a situation has been described, e.g., for Rhamnus salici− folius Lesquereux in Hayden, 1868 from the Maastrichtian of North Dakota (Peppe et al. 2007). On the other hand, it is not excluded that species may be predominantly serrate or pre− dominantly integrimarginate; or else that some species may be indistinctly serrate and integrimarginate and other exclu− sively either serrate or integrimarginate. ...
Article
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Latest Cretaceous (Campanian to Maastrichtian) leaf fossil assemblages are described from 33 exposures ranging from the southern border of the Holy Cross Mountains (southern Poland) through the Roztocze region (south-eastern Poland) to the vicinity of L'viv (western Ukraine). The fossil assemblage is allochthonous, preserved in marine sediments, yet complete compound leaves strongly argue for the transport having been short. Krasnobród and Potelych (Potylicz) are the richest localities; both are late Campanian. The abundance of angiosperm remains in this period is explained by a marine lowstand resulting in nearby emergent vegetated areas. The flora was composed of ferns (three species), conifers (five species, including the commonest Geinitzia reichenbachii), dicotyledons (seventeen taxa; Debeyapaulinae sp. nov., two other species of Debeya, and Rarytkinia polonica being the most frequent), and a single presumed monocotyledon. The eudicot clade is formalised as supersubclass Eudicotyledoneae Doyle and Hotton ex Halamski, herein. The approximately equal abundance of serrate/lob ate and entire-margined dicots attests to an intermediate character of the flora between more thermophilic and polar vegetation. The material may have come from at least two communities: xeromorphic mixed Debeya-coniier forests and platanoid-Lauraceae forests growing in disturbed environments along rivers. The assemblage is most similar to approximately coeval floras from Westphalia and the Netherlands.
... Bobrov 1974), are useful for recognising even small fragments of leaf compressions showing epidermal anatomy and for differentiating such leaf fossils from morphologically similar but quite differently allied extinct Bennettites with syndetocheilic stomata (Thomas & Bancroft 1913, Florin 1933, Harris 1964, 1969. Leaf epidermal research focusing on the phylogenetic history of this ancient group of gymnosperms has been done in many palaeobotanical studies of fossil remains recovered mainly from the Mesozoic (e.g. Watson & Sincock 1992, Peppe et al. 2007). Cenozoic records based on sterile leaf fragments have only recently been accepted as a serious basis for deciphering the evolution and dispersal of cycads. ...
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New compression leaf material of Ceratozamia (Zamiaceae) has been recognised in the European Cenozoic. A leaflet of Ceratozamia floersheimensis (Engelhardt) Kvaček was recovered among unidentified material from the Oligocene of Trbovlje, former Trifail, Slovenia, housed in old collections of the Austrian Geological Survey, Vienna. It is similar in morphology and epidermal anatomy to other specimens previously studied from the lower Oligocene of Flörsheim, Germany and Budapest, Hungary. A fragmentary leaflet assigned to C. hof-mannii Ettingsh. was recovered in the uppermost part of the Most Formation (Most Basin in North Bohemia, Czech Republic) and dated by magnetostratigraphy and cyclostratigraphy to CHRON C5Cn.3n, that is, the latest early Miocene. It yielded excellently preserved epidermal structures, permitting confirmation of the generic affin-ity and a more precise comparison with this lower Miocene species previously known from Austria (Münzenberg, Leoben Basin) and re-investigated earlier. Both the Oligocene and Miocene populations of Ceratozamia are based on isolated disarticulated leaflets matching some living representatives in the size and slender form of the leaflets. Such ceratozamias thrive today in extratropical areas near the present limits of distribution of the genus along the Sierra Madre Orientale in north-eastern Mexico, in particular C. microstrobila Vovides & J.D. Rees and others of the C. latifolia complex, as well as C. hildae G.P. Landry & M.C. Wilson ("bamboo cycad"). The occurrence of Ceratozamia suggests subtropical to warm-temperate, almost frostless climate and a high amount of precipitation. The accompanied fossil vegetation of both species corresponds well with the temperature regime. While the Oligocene species in Hungary probably thrived under sub-humid conditions, the remaining occurrences of fossil Ceratozamia were connected with humid evergreen to mixed-mesophytic forests.
... Several Late Cretaceous and Cenozoic leaves with a broad blade and parallel-pinnate venation have been assigned to Zingiberales (e.g. Hickey & Peterson 1978;Peppe et al. 2007;Kunzmann 2012). These differ from O. ferreri and other Araceae in the characters discussed under living Zingiberales (Coiffard et al. 2013;Kva cek & Smith 2015). ...
Article
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Phylogenetic analyses imply that monocots were a key group in the early radiation of angiosperms, yet they are much rarer than other major clades in the Early Cretaceous macrofossil record. Here we describe a well-preserved leaf and several inflorescences related to the near-basal monocot family Araceae and abundant monocot leaves of uncertain affinities from two latest Albian localities in north-eastern Spain. Orontiophyllum ferreri sp. nov. has a multistranded midrib, several orders of parallel-pinnate veins, two orders of transverse veins, and paracytic-oblique stomata. This suite of characters (but with both anomocytic and paracytic-oblique stomata) is characteristic today of Orontium in the near-basal araceous subfamily Orontioideae, and later Cretaceous and early Cenozoic leaves assigned to Orontiophyllum have similar architecture. Sedimentology and anatomy suggest a (semi)aquatic ecology. Other monocot leaves at the same locality are linear and parallel-veined but have similar stomata. Although anomocytic stomata have been proposed as ancestral in monocots, O. ferreri, the associated linear leaves, Albian–Cenomanian cuticles from Australia and Portugal, and extant data are consistent with the hypothesis that variable paracytic-oblique stomata are ancestral. Turolospadix bogneri gen. et sp. nov., from the other locality, includes spadices of ebracteate flowers with four tepals, a central gynoecium, and a long stipe (vs a spathe attached just below the fertile zone as in most Araceae). Phylogenetic analyses indicate that the character combinations seen in O. ferreri and T. bogneri are ancestral for Araceae, and they could be either sister to Araceae or nested within a basal grade of the family. Together with fossils from the Aptian–Albian of Brazil and Portugal, the Spanish fossils indicate that Araceae are among the oldest extant monocot families, but they were associated with diverse linear-leaved monocots of uncertain affinities.
... Fossil records ascribed to Glyptostrobus date back to the Cretaceous and the genus has been reported from western Canada, and northwestern USA (Van Boskirk, 1998;Bell, 1957;Johnson, 2002Johnson, , 2003Peppe et al., 2007;Ward, 1899), and from the Early Cretaceous to the Early Pleistocene of the middle to high latitudes of North America and Eurasia (LePage, 2007). These fossil remains including leafy shoots, seed cones, pollen cones and wood remains of Glyptostrobus, are often found in association with those of Metasequoia, Sequoia, and Taxodium (Florin, 1922;Becker, 1969;Matsuo, 1970;Schweitzer, 1974;WGCPC, 1978;Guo and Li, 1979;SIGMR, 1980;Li and Yang, 1984;Guo et al., 1984;Tao and Xiong, 1986;Tao, 1994, 1997;Guo, 2000;Vikulin et al., 2007Vikulin et al., , 2008Vikulin et al., , 2010Vikulin et al., , 2011Wang et al., 2010). ...
Article
Conifer remains including petrified wood resembling Sequoia, and leafy shoots and seed cone scales of Glyptostrobus (Cupressaceae s.l.) were found in the late Paleocene Fort Union Formation (Tongue River Member) in the Powder River Basin of Wyoming, northwestern USA. These findings indicate either a wider distribution of both Sequoia and Glyptostrobus in the late Paleocene compared with narrow habitat of modern genera, or possibly that Glyptostrobus-like cones were borne on trees with wood resembling that of Sequoia. The well-preserved wood is assigned to the new species Sequoioxylon carneyvillense sp. n. while the cone fragments and foliage are assigned to Glyptostrobus europaeus (Brongniart) Unger. Wood anatomical features of extant cupressaceous genera including Glyptostrobus, Metasequoia, Sequoia, Sequoiadendron and Taxodium were studied to provide more information for the identification of fossils.
... Marine influence on temperatures became much less homogeneous, with potentially as much as a 10°C difference in submarine water masses between the north and south sides of the isthmus. Terrestrial floras began to demonstrate this influence by presence of northern (Arctic) plant assemblages such as the Nilssonia or Nilssoniocladus species (Peppe et al., 2007) assemblage (Spicer and Herman, 2010). This relationship was demonstrated using clumped isotope data from Campanian and Maastrichtian specimens including Fox Hills marine and estuarine fossils (Petersen et al., 2016, fig. ...
Article
In midcontinent North America, the Fox Hills Formation (Upper Cretaceous, upper Maastrichtian) preserves the last marine faunas in the central Western Interior Seaway (WIS). Neritoptyx hogansoni new species, a small littoral snail, exhibited allometric change from smooth to corded ornament and rounded to shouldered shape during growth. Specimens preserve a zig-zag pigment pattern that changes to an axial pattern during growth. Neritoptyx hogansoni new species was preyed on by decapod crustaceans, and spent shells were occupied by pagurid crabs. Dead mollusk shells, particularly those of Crassostrea subtrigonalis (Evans and Shumard, 1857), provided a hard substrate to which they adhered on the Fox Hills tidal flats. This new neritimorph gastropod establishes a paleogeographic and chronostratigraphic proxy for intertidal conditions on the Dakota Isthmus during the late Maastrichtian. Presence of a neritid extends the marine tropical/temperate boundary in the WIS northward to ~44° late Maastrichtian paleolatitude. Late Maastrichtian closure of the isthmus subsequently altered marine heat transfer by interrupting northward flow of tropical currents from the Gulf Coast by as much as 1 to 1.5 million years before the Cretaceous ended. UUID: http://zoobank.org/3ba56c07-fcca-4925-a2f0-df663fc3a06b
... Other studies that help to define the Fox Hills invertebrate fauna have included treatment of echinoids (Holland and Feldmann, 1967;Rendall et al., 2010), crabs (Feldmann et al., 1976;Tucker et al., 1987;Crawford et al., 2006), Bryozoa (Cuffey et al., 1981), and trace fossils (Daly, 1991). The megaflora of the Fox Hills Formation was identified by Peppe and Erickson (2002) and Peppe et al. (2007). Erickson et al. (2010) reported on the palynomorphs from the Linton Member of the formation. ...
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ABSTRACT As part of a study of the Vertebrata found in the Late Cretaceous (Early Maastrichtian to Middle Late Maastrichtian) Fox Hills Formation, 48 sites in western and central North Dakota were collected to interpret the chondrichthyan and osteichthyan paleofaunas. Based mostly on teeth, 19 shark species, 16 skate and ray species, and one ratfish species were recognized. Of those, three taxa are new, including Cretalamna feldmanni n. sp., “Myliobatis” foxhillsensis n. sp., and Dasyatis northdakotaensis n. sp. New chondrichthyan species occurrences for the Fox Hills Formation include: Squalus ballingsloevensis, Plicatoscyllium derameei, Cretorectolobus olsoni, Carcharias cf. C. tenuiplicatus, Cretalamna feldmanni n. sp., Paranomotodon toddi, Squalicorax pristodontus, Palaeogaleus navarroensis, Archaeotriakis rochelleae, Paraorthacodus andersoni, Synechodus turneri, Walteraja exigua, Dasyatis northdakotaensis n. sp., Rhombodus levis, “Myliobatis” foxhillsensis n. sp., and morphotypes of placoid scales and dermal denticles. Twenty species of bony fishes were identified from teeth and other skeletal parts, two were vertebral morphospecies, two were based on scales, and four were recognized from otoliths. New osteichthyan occurrences in the Fox Hills Formation include: a lepisosteid, Melvius sp., Cyclurus fragosus, Protosphyraena sp., Belonostomus longirostris, Xiphactinus vetus, Paratarpon? sp., Pollerspoeckia siegsdorfensis, cf. Bathylagus sp., Enchodus cf. E. ferox, and “Apogonidarum” maastrichtiensis. The Fox Hills Formation is Early Maastrichtian in Bowman County, southwestern North Dakota. The Bowman County sites yielded the oldest fossils of this study. Sites in the Fox Hills type area in north-central South Dakota and south-central North Dakota are Middle Late Maastrichtian based on the presence of Hoploscaphites nicolletii and Hoploscaphites nebrascensis Ammonite Zones and the Wodehousia spinata Pollen Zone. Age relationships of these fossil sites suggest temporal range extensions for several of the Fox Hills fish taxa. Fox Hills fishes were derived from deep and shallow marine, brackish, and freshwater habitats. Five groupings were identified based on qualitative assessment of these habitat preferences. These groupings are: “offshore marine,” “nearshore marine,” “brackish water/estuarine–strong tidal influence,” “brackish water/estuarine–weak tidal influence,” and “riverine/lagoonal–strong freshwater influence.” Tooth morphology and comparison to modern analogs indicate presence of the following feeding types: omnivore, general invertebrate, molluscivore, pelagic piscivore, benthic piscivore, and scavenger. Species representing all feeding types occur in each of the five habitat groupings. Feeding competition was thus partitioned by habitat preference. When coupled with paleogeographic distribution information, the Fox Hills fish fauna indicates that some taxa represent a recurring assemblage of species that have a “large-river delta” habitat preference, as found today on major deltas of most continents. Paleogeographic conditions in the Western Interior Seaway (WIS) were dominated by the physiographic conditions of the Hell Creek Delta and Dakota Isthmus complex, which is composed of lagoons, estuaries, and barrier island shorelines. The Fox Hills fish paleofauna includes taxa restricted to the WIS and those that also occurred in the Texas Gulf Coast, Mississippi Embayment, Atlantic Coastal Plain, Greenland, and Sweden. Pelagic, deep marine lamniform species were cosmopolitan and ranged to Europe and North Africa. The Fox Hills fish fauna is most similar to the fish faunas of the Maastrichtian Kemp Formation, Texas, Severn Formation, Maryland, and Navesink and New Egypt formations, New Jersey. The Fox Hills paleofauna documents fish extinction at the close of the Cretaceous. None of the 35 chondrichthyan species and none of the 20 osteichthyan species recovered from the Fox Hills Formation are found in the Paleocene worldwide. 58% of Fox Hills chondrichthyan and 77% of osteichthyan genera, and 20% of chondrichthyan and 33% of osteichthyan families, did not survive after the Cretaceous. Support for this interpretation is provided by comparison of the Fox Hills paleofauna to the Paleocene Cannonball Formation paleofauna in North Dakota. None of the 13 Cannonball chondrichthyan species, nor any of the four Cannonball osteichthyan species, occur in the Fox Hills Formation. Thirteen chondrichthyan genera (Squatina, Squalus, Ginglymostoma, Carcharias, Odontaspis, Cretalamna, Palaeogaleus, Galeorhinus, Paraothacodus, Synechodus, Myliobatis, Dasyatis, and Ischyodus) range across the K-Pg boundary.
... This was necessary for dating because no definitive fossils are available to constrain ages within Pomaderreae. Four fossil calibrations from Onstein et al. (2015) and Hauenschild et al. (2018) were used to constrain the topology, namely (1) the Rose Creek flower (Couper, 1960) for the stem of Rhamnaceae (normal prior distribution, mean = 94, S = 1), (2) Rhamnus salicifolius and Coahuilanthus belindae (Peppe et al., 2007) to calibrate Rhamneae and Maesopsideae crown (log-normal prior distribution, offset = 70, mean = 0, S = 1.25), (3) Colubrina spireaefolia (Manchester, 2001) for the Colubrina crown (normal prior distribution, offset = 28.4, mean = 0, S = 1.25), and (4) Ceanothus leitchii and C. precuneatus (Axelrod, 1958) to calibrate the Ceanothus crown (log-normal prior distribution, offset = 12, mean = 0, S = 1.25). ...
Article
Aim Gondwanan biogeographic patterns include a combination of old vicariance events following the breakup of the supercontinent, and more recent long-distance dispersals across the southern landmasses. Floristic relationships between Australia and New Zealand have mostly been attributed to recent dispersal events rather than vicariance. We assessed the biogeographic history of Pomaderris (Rhamnaceae), which occurs in both Australia and New Zealand, by constructing a time-calibrated molecular phylogeny to infer (1) phylogenetic relationships and (2) the relative contributions of vicariance and dispersal events in the biogeographic history of the genus. Location Australia and New Zealand Methods Using hybrid capture and high throughput sequencing, we generated nuclear and plastid data sets to estimate phylogenetic relationships and fossil calibrated divergence time estimates for Pomaderris. BioGeoBEARS and biogeographical stochastic mapping (BSM) were used to assess the ancestral area of the genus and the relative contributions of vicariance vs dispersal, and the directionality of dispersal events. Results Our analyses indicate that Pomaderris originated in the Oligocene and had a widespread Australian distribution. Vicariance of western and eastern Australian clades coincides with the uplift of the Nullarbor Plain c. 14 Ma, followed by subsequent in-situ and within-biome diversification with little exchange across regions. A rapid radiation of southeastern Australian taxa beginning c. 10 Ma was the source for at least six independent long-distance dispersal events to New Zealand during the Pliocene–Pleistocene. Main conclusions Our study demonstrates the importance of dispersal in explaining not only the current cross-Tasman distributions of Pomaderris, but for the New Zealand flora more broadly. The pattern of multiple independent long-distance dispersal events for Pomaderris, without significant radiation within New Zealand, is congruent with other lowland plant groups, suggesting that this biome has a different evolutionary history compared with the younger alpine flora of New Zealand, which exhibits extensive radiations often following single long distance dispersal events.
Article
A new wood type for the Baja California Cretaceous adds to the plant diversity so far known for the area where gymnosperms seem to be dominant. It was collected near El Rosario, Baja California, from rocks of the Rosario Formation, in a sedimentary sequence that comprises ca. 1200 m of non-marine to deep marine sediments from Upper Campanian to Lower Danian age. The wood is characterized by having semiring porous growth rings, predominantly radial multiples of 2–7 with occasional clusters and some solitary vessels, simple perforation plates, alternate intervascular pits, oval to large elliptical vessel element-ray pits with reduced borders, septate thin-walled fibers, 1–4 seriate heterocellular rays, scares paratracheal, vasicentric and marginal parenchyma and oil cells associated with ray parenchyma. All these characters are found in Lauraceae, however, none of the extant taxa of the family have all these characters and even among fossil woods the characters in the Baja California material are better described only among the diverse Laurinoxylon, but vessel grouping, growth ring type, absence of marginal parenchyma, and slightly thicker rays suggest the presence of a new taxon, Rosarioxylon bajacaliforniensis Cevallos-Ferriz, Catharina & Kneller. By the end of the Cretaceous the family formed part of the plant community that represents a western extension of vegetation types more completely described from areas in the margins of the southern limits of the Western Interior Sea. The new taxon is proposed to highlight anatomical differences and geographic isolation from similar taxa and further suggests a large distribution of Lauraceae in what appears to be conifer dominated communities.
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Cambridge Core - Palaeontology and Life History - Early Flowers and Angiosperm Evolution - by Else Marie Friis
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The Hell Creek Formation in eastern Montana has yielded well-preserved leaf megafossil localities that provide insight into the vegetation and climate of the latest Cretaceous. Among the most basal, the PDM locality (UCMP [University of California Museum of Paleontology] PB99057 = MOR [Museum of the Rockies] HC-278) occurs in channel sandstones ∼10 m above the underlying Fox Hills Formation. The locality represents a fluvial/estuarine environment. Leaf megafossil impressions were preserved on clay drapes within the channel. Angiosperms dominated the flora (13 of 17 morphotypes). Dryophyllum subfalcatum and "Vitis" stantoni, two common morphospecies in the Hell Creek Formation, are well represented. Gymnosperms including Metasequoia, Glyptostrobus, Cupressinocladus, and Ginkgo are rare; ferns and cycadophytes are absent. Univariate leaf-margin analysis produced mean annual temperature (MAT) estimates of ∼7-11 °C (5-14 °C including overlapping estimation errors). The Climate Leaf Analysis Multivariate Program (CLAMP) produced a MAT value of 11-12 °C ± 2 °C. Leaf area analysis produced mean annual precipitation (MAP) estimates of 197 cm (+152/-86 cm) and 191 cm (+161/-87 cm), while CLAMP produced a growing season precipitation estimate of 82-90 ± 48 cm. The wetter MAP values are consistent with paleosols near the base of the formation, which lack paleosol carbonate. CLAMP results further suggest seasonality in both temperature and precipitation. Some PDM morphotypes are familiar from the Hell Creek I floral zone of North Dakota, and several are not, suggesting greater spatial and/or temporal heterogeneity in the Hell Creek Formation flora than has been previously appreciated.
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The Winthrop Flora is of middle to late Albian age (Early Cretaceous) and occurs in the Methow basin of north-central Washington State, USA. With an estimated diversity of more than 150 species, the Winthrop is the most diverse flora yet described from the Early Cretaceous of North America. This paper deals with the 38 species of gymnosperms or Pinophytina of the Winthrop Formation, consisting of three species of Pteridospermopsida, three of Cycadopsida, three of Ginkgoopsida, nine of Bennittopsida, 15 of conifers or Pinopsida, and five species whose assignment is uncertain below the level of the gymnosperms. We describe four new genera and 21 new species of Pinophytina. Overall, the gymnosperm component of the flora is concordant with that of other late Early Cretaceous floras of the Northern Hemisphere. However, several of its species are similar to those found in Jurassic sediments from Mexico and Central America and some of the cycadophytes and conifers have what we interpret as xeromorphic foliage.
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An imprint of shoot Nilssoniocladus Kimura et Sekido bearing leaves Nilssonia Brongniart was found for the first time in the Lower Cretaceous deposits of the Markovsky peninsula near the city of Vladivostok. A new species, Nilssoniocladus anatolii, is identified. The finds of such shoots in organic connection with leaves are rare, and new data supplement our knowledge on the diversity, stratigraphic and geographic distribution of the genus Nilssoniocladus. Key wordsEarly Cretaceous–Lipovtsy Formation– Nilssoniocladus –Southern Primorye
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Rich paleobotanical localities of eastern Asia and western North America provide ample opportunities for documentation and analysis of trans-Beringian migration and differentiation. Species-level comparisons are made for cupressaceous conifers Mesocyparis and Ditaxocladus , as well as for the platanoid genera Macginitiea and Platimeliphyllum . Asiatic and American species (forms) of these genera are interpreted as representing successive speciation events en route from northeastern Asia to North America ( Mesocyparis rosanovii – M. beringiana – M. borealis and Platimeliphyllum valentinii – P. palanense – Platimeliphyllum sp. from Fushun and Clarno) or, alternatively, a divergent speciation over the trans-Beringian ranges, as in Ditaxocladus . A new species of cupressaceous conifer from the Paleocene of Amur Province is recognized: Ditaxocladus kivdensis sp. nov. The dominant latest Cretaceous–Paleocene group of trochodendrocarpoids ( Trochodendroides type leaves, Trochodendrocarpus , Joffrea and Alasia reproductive structures) shows a generic-level differentiation across Beringia attesting to periodic rather than permanent floristic connections. The aquatic/semiaquatic congeners had appeared on both sides of the bridge with the rise of floating plant biomass in the mid-Cretaceous, then synchronously entering the Late Cretaceous (Quereuxia) and terminal Cretaceous ( Limnobiophyllum , Cobbania ) stages. The trans-Beringian continuity of aquatic vegetation might have been sustained by dinosaur migrations. Cobbania was lost to the end-Cretaceous extinction, but trochodendrocarpoids culminated at the boundary attesting to a widespread temperization of global climates.
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A new tribal classification of Rhamnaceae based on a phylogenetic analysis of rbcL and trnL-F sequences of the plastid genome is outlined here. The last classification of the family by Suessenguth recognised five tribes. Eleven tribes are now recognised, three of which are new (Ampelozizipheae, Doerpfeldieae and Bathiorhamneae). The constitution of Rhamneae Hook. f. has been emended, and the name of one tribe has been corrected Zizipheae Brongn. to Paliureae Reissek ex Endl.; as suggested by Schirarend & Olabi 1994) and emended. Ventilagineae Hook. f., Colletieae Reissek ex Endl. and Gouanieae Reissek ex Endl. are retained. Pomaderreae Reissek ex Endl. and Maesopsideae Weberb. have been resurrected, as has Phyliceae Reissek ex Endl., which has also been emended. Three larger groups within Rhamnaceae are also described on the basis of the molecular data. However, there are no morphological characters marking these groups, and they are therefore given informal names in this treatment. A morphological cladistic analysis also included here demonstrates the problems of attempting phylogenetic reconstruction if only a few morphological characters are available.
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Abstract--The latest Maestrichtian marine deposition in the Western Interior is represented by the Fox Hills Formation in North and South Dakota, which contains a relatively large, nearshore molluscan fauna. Restudy of the Gastropoda from the Fox Hills Formation in North Dakota indicates a fauna of at least thirty-seven species in twenty-four genera and has introduced eleven new generic-level taxa to the record from the North Dakota Maestrichtian. These genera include Neritina, Syncera, Cancellaria, Remera?, Amuletum, Semitriton, Hecorhyncus, Rhombopsis, Graphidula, Perissitys, and Goniocylichna, and are based both on reassignment of known faunal elements and discovery of previously unknown taxa. Paleozoogeographic distributions based upon the published literature indicate that the Fox Hills gastropod fauna had a strong contribution from Gulf Coast and Mississippi Embayment stock with a lesser contribution coming from faunal sources to the northwest. Species from Gulf Coast lineages show a marked reduction of shell ornament, a cold-water feature, indicating that by Fox Hills time in North Dakota the Maestrichtian regression was well in progress with seaway connections to the Gulf Coast already severed to produce a northward regression and to subject the area solely to the influence of cold-water marine conditions from the northwest. These cold-water conditions may reflect a latitudinal climatic gradient but it is equally likely that they were a response to marine current flow and thus may have been the cause of, rather than the result of, climatic effects as suggested by some workers and as postulated herein. The last southern connections of the seaway were to the southeast where two species, Euspira rectilabrum (Conrad), and Goniocylichna bisculpturata Wade, of the Ripley Formation occur in the Fox Hills Formation in North Dakota. Since migration directions are reversible, and because Maestrichtian faunas to the northwest are still poorly understood, it is recognized that G. bisculpturata may have had origins from either source.
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Details for recognition of the Dakota Isthmus as a significant Maastrichtian paleogeographic feature at the close of the Western Interior Seaway are provided.
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ABSTRACT--The marine bivalves Clisocolus moreauensis, Cuspidaria ventricosa, and Periploma (Aelga?) subgracile are recorded from the Fox Hills Formation (Maestrichtian) in Emmons County, North Dakota, for the first time. C. moreauensis was taken from a fossil-rich concretion zone, also con raining many Sourimis equilateralis and Hoploscaphites nicolleli, in a silty shale very low in the section. The fauna is characteristic of the lower nicolleti Assemblage Zone and constitutes the first biostratigraphic evidence supporting recognition of the lower Trail City Member in the state. Arctica cf. A. ovala, typically a Cannonball (Paleocene) species, is recorded for the first time in the Fox Hills Formation in Emmons and Sioux Counties, North Dakota. This species, in consort with Periploma subgracile, increases the already high degree of similarity between Fox Hills and Cannonball bivalve faunas. C. moreauensis, S. equilatet dis, P. sub,¢racile, and A. ovala are elements of the North American Boreal Faunal Province and indicate close ties with Late Campanian-Maestrichtian faunas of Canada, although in the Fox Hills they are mixed at times with species having Gulf Coast origins. Presence of Arctica indicates temperate water conditions existed in North Dakota above the Sphenodiscus lent£mlaris ammonite zone. Linkage with the Gulf Coast ceased late in Fox Hills time when deltaic deposition along and against the Sioux Arch joined the eastern and western strands. The Dakota Isthmus, a broad tidal floodplain dominated by brackish faunas, resulted from this union and separated the regressing sea into northern and southern basins at 45° latitude. Northward marine connections through the Canadian Arctic and Hudson Bay were terminated, but the Hudson Bay connection was reestablished in Paleocene time providing a marine entry to the Williston Basin across the Canadian Shield. The resulting Cannonball Sea had a temperate fauna with a composition similar to those of the Paleocene Paris Basin.
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ABSTRACT--General sedimentologic, stratigraphic, and paleontologic relationships represented by the Fox Hills Formation (Late Cretaceous: Maastrichtian) in the type area of North Dakota and South Dakota have been described over the last half-century based upon studies by numerous workers in several loci of bedrock outcrop. The process of description of the primary Fox Hills exposures in the Missouri Valley region and lesser exposure in eastern Montana and the Fairpoint and Stoneville Quadrangles of South Dakota has created a disjunct image of the stratigraphy and deposystem of this formation. The present paper calls attention to the questions raised by this disjunct pattern of knowledge and presents some data that contribute to a more unified, or holistic, interpretation of the formation. Although most pieces of the stratigraphic puzzle are known, the whole picture has not yet been assembled, as it were. A few key pieces are still missing. Most of these must be supplied by subsurface study of the formation. Examination of the Fox Hills and contiguous formations underlying Hettinger, Adams, Stark, Mercer, Oliver, Morton, Burleigh, Logan, Grant, and portions of Sioux and Emmons Counties, North Dakota, using structural, isopachous, and lithologic data, demonstrates that the classic member terminology and facies relationships of exposures in the Missouri Valley in North Dakota and South Dakota are not indicative of the formation in the subsurface regionally. A Wide area of Hettinger, Stark and Grant Counties is underlain by organic-rich brown and green silt and shale facies indicative of interdistributary bay depositionai conditions. These represent undescribed unit(s) Within the Fox Hills-Hell Creek deposystem. Distributary channel facies and associated crevasse splay sandstones outline the region along its northern, western and southern margins. A particularly thick, distributary channel sand body invaded the bay from the north and now underlies Mercer and Oliver Counties. This unit has been termed "Colgate" Member in the region, but its petrologic and stratigraphic affinities With that unit are yet to be determined. Percent sandstone isopleths define the delta front-lower delta plain deposystem well. Structural contours and first-sand maps demonstrate that Fox Hills sedimentation was partially controlled by structural highs penecontemporaneously developing on the Pierre Shale. Mild effects of Laramide tectonism continued to influence the Wiiliston Basin during, and presumably after, Fox Hills time. Elongate patterns on isopachous maps reflect depositional responses to movements of basement blocks. In Emmons County relationships suggest that nondepositon, or erosion, may have been involved in the uneven distribution of the Linton volcanic ash in a trough-shaped, estuary-like body. Facies patterns and paleogeography in southeastern portions of the study area were controlled by a platform related to the Transcontinental Arch which trapped sands and resulted in formation of a Wide, sea level coastal marsh. Against this the Fox Hills-Hell Creek Delta prograded, coalescing to produce closure of the Fox Hills Seaway and division of the Late Cretaceous Interior Seaway into northern and southern basins. An elongate estuary, open to the northeast, was reinvaded as subsidence and/or tectonic adjustment occurred in the region, depositing tongues of marine sediment Within the Hell Creek Formation. These conditions gradually migrated northeastward leaving a vegetated plain, the Dakota Isthmus, behind as the Cretaceous ended. A persistent southwest to northeast drainage pattern was established.
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The Grebenka flora, from the main exposure of the Albian–Cenomanian Krivorechenskaya Formation in northeastern Russia, represents a range of plant communities from pioneer to mature forest that grew close to the mid-Cretaceous North Pole (>72°N). The diversity of this flora is dominated by angiosperms followed by conifers, ferns and other plant groups. The age is constrained by 40Ar/39Ar analyses of associated volcaniclastics (∼96.5 Ma), coupled with biostratigraphic correlation of the plant-bearing non-marine beds with marine units of the Krivorechenskaya Formation and the overlying Dugovskaya Formation. Limited palaeosol development and pronounced episodic floodplain aggradation indicate that the 100-m-thick plant-bearing volcaniclastic floodplain succession was deposited rapidly, resulting in excellent trapping and preservation of the plant communities, but dilution of the palynoflora. Analysis of the megaflora (>100 foliage taxa, plus woods and fructifications) provides a ‘snapshot’ of the mid-Cretaceous climate, and offers reliable quantitative climatic signals of conditions near the mid-Cretaceous North Pole. Multivariate analysis of leaf physiognomy (Climate Leaf Analysis Multivariate Program) on the whole flora suggests that the plants experienced a mean annual temperature of 13.0±1.8°C and a cold month mean temperature of 5.5±3.3°C. However, analyses of individual florules yield slightly different results that help constrain the uncertainties inherent in such an approach. These and other foliar physiognomic data are compared across the Arctic.
Article
Two new Nilssoniocladus species are erected based on the well preserved specimens collected from the Tochikubo Formation (Oxfordian), Soma-Nakamura Group, Northeast Honshu, Japan. Both Nilssoniocladus tairae sp. nov. and N. japonicus sp. nov. are represented by long and short shoots terminally with a rosette of leaves. Detached leaves of Nilssoniocladus were piled up on the bedding planes, forming so called 'Nilssonia' mats which suggest that the leaves of both species are deciduous like those of the type species. The slender habit of long shoots suggests that Nilssoniocladus plants are climbers.
Chapter
The Hell Creek and Fort Union Formations in southwestern North Dakota and northwestern South Dakota have yielded a diverse megaflora of 380 species from 158 quarry sites. These sites are situated in a stratigraphic framework, delimited by palynology, magnetostratigraphy, and vertebrate paleontology, that contains both the Cretaceous-Tertiary (K-T) boundary event horizon and stratigraphic evidence for rapid base-level increase. The late Maastrichtian Hell Creek flora is dominated by angiosperms; ferns, fern allies, cycads, ginkgo, and conifers represent <10% of total taxa and specimens. Megafloral extinction at the K-T boundary is extensive, effectively eliminating all dominant plant taxa of the upper Hell Creek Formation. K-T survivorship appears to be greatest in plants that occupied Cretaceous mire facies. The Hell Creek megaflora is heterogeneous with respect to stratigraphic position and sedimentary facies, allowing the recognition of three superposed megafloral zones and two facies-controlled megafloras. Hell Creek vegetation represents an angiospermdominated woodland composed of small-to medium-sized trees, often with lobed leaves. One exception is a diverse angiosperm-dominated herbaceous vegetation associated with large paleochannels in the middle of the formation. The uppermost Hell Creek megaflora zone (HCIII) first occurs near the base of magnetic polarity subchron C29R. The HCIII megaflora is significantly more diverse than earlier Hell Creek floras, and foliar physiognomy suggests a significant climate warming during the final 300-500 k.y. of the Cretaceous. The Paleocene megaflora is depauperate, less heterogeneous than the Cretaceous megaflora, and dominated, in all facies, by taxa that were most common in Cretaceous mire facies.
Chapter
In North Dakota, the Hell Creek Formation is a Laramide clastic wedge of primarily nonmarine strata intercalated with marine and brackish facies. The formation ranges in thickness from 100 to 60 m on a west to east transect across the southern portion of the state and tongues within the Hell Creek represent the youngest Cretaceous marine strata in the Western Interior. Hell Creek strata consist of poorly cemented fine-grained sandstone, siltstone, and carbonaceous-rich shale, mudstone, claystone, and rare lignite. These sedimentary rocks were deposited primarily in laterally accreting fluvial channel systems and associated flood plains. Although localized stratigraphic patterns were recognized within the 76 sections measured for this study, no regional trends or marker horizons were observed. The marine Breien Member, formally proposed in 1942, maintains its integrity in outcrop over an area of at least 6000 km2 in south-central North Dakota and is the only valid member of the Hell Creek Formation. The Cantapeta Tongue, a marine brackish-water tongue characterized by Ophiomorpha and named herein, is present 16 m below the top of the Hell Creek Formation (40 m above the Breien Member and 20 m below the base of the Paleocene Cannonball Member [Fort Union Formation]). These occurrences of marine or brackish-water strata near both the base and top of the Hell Creek Formation in south-central North Dakota suggest that the Fox Hills Sea may not have withdrawn completely from the area before the advance of the Cannonball Sea in Paleocene time. Dinosaur remains are found throughout the Hell Creek Formation in North Dakota but are clustered within 20 m of the base of the formation in the south-central portion of the state where the fossils are concentrated a few meters above and below the Breien Member.
Article
Nine genera of fossil palm and palm-like leaves are recognized in this study. Amesoneuron H. R. Goeppert, Bactrites E. W. Berry, Palmacites A. Brongniart, Phoenicites A. Brongniart, and Sabalites G. Saporta are considered to be true palms. Some specimens, because of their uniquely recognizable characteristics, have been identified with the modern genus Phoenix Linnaeus. Sanmiguelia R. W. Brown, Paloreodoxites F. Knowlton and Propalmophyllum O. Lignier are also included in this study because of their superficial resemblance to palms. However, they lack one or more characters essential for their recognition as true palms (i.e. hastula, primary costa, and two orders of venation paralleling a prominent but uniform mid-vein in the individual segments). A diagnostic key and a synopsis of accepted form and organ genera, with appropriate synonymies and new combinations complete the paper. A list of genera to be excluded from the Palmae is appended.
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Coherent patterns of morphology of apparent value in determining taxonomic and phylogenetic relationships are present in dicotyledonous leaves. Features of greatest value in assessing these affinities include leaf organization; marginal features, including morphology of the tooth; major vein configuration; characters of the intercostal venation; and gland placement. Of these, recognition of tooth morphology appears to be an overlooked tool of major systematic importance. Variation in these features is most coherent when analyzed in terms of the Takhtajan and Cronquist systems of dicot classification. Essential to our procedure was a recognition of the "basic" leaf features of each taxon. These were regarded as the most generalized type from which all of the more specialized types in a taxon could have been derived and they were derived from an analysis of the comparative morphology of modern leaves with limited input from the fossil record. The resulting scheme indicates strong correlation of leaf features with six of the seven Takhtajan subclasses, in addition to paralleling and clarifying both systems at the ordinal and familial levels. Conspicuous exceptions are the breakdown of the Asteridae into a possible rosid and a possible dilleniid group, reassignment of the Celastrales and Myrtales to the Dilleniidae, and of the Juglandales to the Rosidae. Affinities of numerous problem taxa, such as the Didymelaceae and Medusagynaceae, are resolved, as are some of the points of disagreement between the Takhtajan and Cronquist arrangements. This analysis also provides the first systematic summary of dicot leaf architectural features and the outlines of a regular systematic method for leaf determination.
Article
A B S T R A C T A classification of the architectural features of dicot leaves-i.e., the placement and form of those elements constituting the outward expression of leaf structure, including shape, marginal configuration, venation, and gland position-has been developed as the result of an extensive survey of both living and fossil leaves. This system partially incorporates modifications of two earlier classifications: that of Turrill for leaf shape and that of Von Ettingshausen for venation pattern. After categorization of such features as shape of the whole leaf and of the apex and base, leaves are separated into a number of classes depending on the course of their principal venation. Identification of order of venation, which is fundamental to the application of the classification, is determined by size of a vein at its point of origin and to a lesser extent by its behavior in relation to that of other orders. The classification concludes by describing features of the areoles, i.e., the smallest areas of leaf tissue surrounded by veins which form a contiguous field over most of the leaf. Because most taxa of dicots possess consistent patterns of leaf architecture, this rigorous method of describing the features of leaves is of immediate usefulness in both modern and fossil taxonomic studies. In addition, as a result of this method, it is anticipated that leaves will play an increasingly important part in phylogenetic and ecological studies.
Article
A new plant from the Los Ahuehuetes locality, near Tepexi de Rodríguez, Puebla, Mexico, is described based on its leaves. They are characterized by being ovate to elliptic, 4.5 cm long by 2.1 cm wide, having an entire margin, eucamptodromous venation, a midvein that is slightly curved and attenuated towards the leaf apex, seven pairs of secondary veins diverging at an acute angle from the midvein, percurrent tertiary veins forking or sometimes reticulated forming areoles, and having a petiole 1.3 cm long and 0.3 cm wide. An agglomerative nonhierarchical analysis with average linkage, based on the definition of 41 character states in 18 operational taxonomic units allows distinction between Karwinskia, Berchemia, and Rhamnus; the recognition of an extinct monotypic genus, Berhamniphyllum; and the identification of two fossil species of Karwinskia, among which the new plant from Puebla, Karwinskia axamilpense Velasco de León et al., is well defined. This new fossil leaf not only adds to the recently known Tertiary plants of the Los Ahuehuetes locality, but it gives new insights into the past flora of tropical North America and further supports the long history of some neotropical endemics, suggesting that, during the Tertiary, at least some areas in southern latitudes of North America could have been important for the origin and radiation of some taxa.Key words: Oligocene, Mexico, paleobotany, Rhamnaceae, Karwinskia.
Article
Zingiberopsis attenuata Hickey and Peterson is a new species of monocotyledon from the Paleocene Paskapoo Formation of Alberta. Leaves of this species with their parallel veins grouped into three size sets are intermediate between the Late Cretaceous Zingiberopsis magnifolia (Knowlton) Hickey, new combination, with four discrete sets and Zingiberopsis isonervosa Hickey, of late Paleocene and early Eocene age, with only one set. Zingiberopsis has large, elliptic to ovate leaves with a costa composed of a number of concurrent strands, a set of parallel veins emerging at low angles from the costa, and relatively distantly spaced transverse veins running between adjacent parallel veins. Morphology of the genus matches that of Alpinia in the Zingiberaceae except for greater irregularity of the parallel vein set at and near their origin on the costa and the lack of any evidence of a ligule on the petiole as in Alpinia. Species of Zingiberopsis demonstrate a clear trend toward loss of the wider parallel vein subsets over the approximately 20-million-year range of the genus. In addition, the overlooked character of the arrangement of the parallel vein subsets across the width of the leaf may have potential in the taxonomic determination of monocotyledonous leaves.
Article
The remarkable organs which are frequently associated with the Zamia gigas of Lindley and Hutton, and which have always been considered as in some way connected with the fructification of that plant, are the only fossils that can be referred to Cycadean fruits that have been hitherto observed in the Yorkshire Oolites, in which the remains of Cycadean leaves are so abundant. These organs have been made the subject of an elaborate memoir by Professor Williamson, presented to the Linnean Society some months since, and which it is to be hoped will soon appear in the Transactions of that Society. He has brought together so many observations, made during a life-acquaintance with these beds, that he has been able to re-construct, with every appearance of truth on his side, a singular genus, containing two well-marked species, and forming a new tribe of Cycadeœ very different from any living form.
Article
  A new species of chimaeroid, Ischyodus rayhaasi sp. nov., is described based primarily upon the number and configuration of tritors on palatine and mandibular tooth plates. This new species is named in honour of Mr Raymond Haas. Fossils of I. rayhaasi have been recovered from the Upper Maastrichtian Fox Hills Formation and the Breien Member and an unnamed member of the Hell Creek Formation at sites in south-central North Dakota and north-central South Dakota, USA. Ischyodus rayhaasi inhabited shallow marine waters in the central part of the Western Interior Seaway during the latest Cretaceous. Apparently it was also present in similar habitats at that time in the Volga region of Russia. Ischyodus rayhaasi is the youngest Cretaceous species of Ischyodus known to exist before the Cretaceous/Tertiary extinction, and the species apparently did not survive that event. It was replaced by Ischyodus dolloi, which is found in the Paleocene Cannonball Formation of the Williston Basin region of North Dakota and is widely distributed elsewhere.
Article
Nilssoniocladus (Kimura and Sekido, 1975) is an important Mesozoic plant because it is widely regarded as representing a deciduous (leaf shedding), frost-resistant cycad. It has been used to argue that evergreenness was not obligatory in Mesozoic cycads and therefore reduced obliquity need not be invoked to explain the observed presence of cycads at high latitudes in the Mesozoic. However, until now the presence of Nilssoniocladus at high latitudes was conjectural.In this paper two new species of Nilssoniocladus are described, one from the latest Albian (?) Lower Killik Tongue of Northern Alaska (palaeolatitude 75°N) and one from the latest Albian-earliest Cenomanian Krivorechenskaya Formation of northeastern Russia (palaeolatitude 73°N) that demonstrate evidence for synchronous leaf shedding (deciduousness) and short shoot abscission. The Alaskan specimens exhibit thin woody stems bearing short shoots with persistent leaf scars and circular scars interpreted as short shoot abscission points. The specimens are associated with mats of Nilssonia leaves. The Russian example of Nilssoniocladus shows evidence of short shoot shedding with the leaves remaining attached to the shed short shoots. The two new species differ from the Japanese material in terms of leaf and leaf scar morphology. Short shoot scars are described for this plant for the first time.Nilssonia leaves are widespread in middle and high northern latitudes throughout the Jurassic and Cretaceous and many of these leaves were produced by the plants represented by the genus Nilssoniocladus. The genus was quite diverse, and comprised a minor, but often locally abundant to subdominant, component of the now extinct deciduous polar forests of the Mesozoic “greenhouse” world.
Article
Thesis (B.S. Geology with Honors)--St. Lawrence University, 2003. Includes bibliographical references (leaves 107-115).